Long-Term Outcomes Associated With DIfferent High-Dose-Rate Brachytherapy Dose Regimens for Favorable and Unfavorable Intermediate Risk Prostate Cancer

Document Type

Conference Proceeding

Publication Date

10-2023

Publication Title

International Journal of Radiation Oncology, Biology, Physics

Abstract

Purpose/Objective(s): To present long-term efficacy outcomes of prostate high-dose-rate (HDR) brachytherapy monotherapy using 38 Gy in 4 fractions, 24 Gy in 2 fractions, and 27 Gy in 2 fractions for men with favorable and unfavorable intermediate risk prostate cancer. Materials/Methods: Patients treated with HDR brachytherapy monotherapy for NCCN favorable (FIR) or unfavorable (UIR) intermediate risk prostate cancer from 1999-2020 were identified in a prospectively maintained, single institution database. Patients with less than two years of follow-up and those treated with single fraction HDR brachytherapy were excluded. Biochemical failure was determined using Phoenix criteria. 10-year biochemical control (BC), local control (LC), and distant metastasis (DM) rates were estimated using the Kaplan-Meier method. Results: Two hundred sixty-seven patients were included. One hundred eighty-nine had FIR and 78 had UIR prostate cancer, with median follow-up of 9.6 years and 7.2 years, respectively. Of the 189 patients with FIR prostate cancer, 59 (31.2%) received 38 Gy in 4 fractions, 26 (13.7%) received 24 Gy in 2 fractions, and 104 (55.0%) received 27 Gy in 2 fractions. Of the 78 patients with UIR prostate cancer, 20 (25.6%) received 38 Gy in 4 fractions, 11 (14.1%) received 24 Gy in 2 fractions, and 47 (60.2%) received 27 Gy in 2 fractions. Date ranges of treatment for the respective fractionation schedules were 1999-2010, 2007-2016, and 2009-2020. Upfront androgen deprivation therapy (ADT) was given to 12 (6.3%) patients with FIR and 10 (12.8%) patients with UIR. 10- year rates of BC for FIR and UIR patients were 90.1% and 78.8% (p = 0.004), respectively. 10-year rates of LC were 92.4% and 85.0% (p = 0.06), respectively. 10-year rates of DM were 1.9% and 4.7% (p = 0.12), respectively. For FIR patients, 10-year BC rates were 96.2% for patients receiving 38 Gy in 4 fractions vs. 86.3% (p = 0.07) for those treated with the 2-fraction regimens, while 10-year LC rates were 97.9% and 89.0% (p = 0.049), respectively. Within the UIR subset, the 10-year BC rates for patients receiving 38 Gy in 4 fractions and patients receiving treatment in 2 fractions were 95.0% and 70.6% (p = 0.038). 10-year LC rates were 100% and 77.8% (p = 0.045), respectively. 10-year BC rates by treatment schedule are shown in the table below. Conclusion: HDR brachytherapy monotherapy results in excellent longterm local control for intermediate risk prostate cancer. Improvements in biochemical and local disease control for patients treated with 38 Gy in 4 fractions warrants consideration of prospective study of optimal treatment dosing regimens.

Volume

117

Issue

2 Suppl

First Page

e433

Comments

American Society for Radiation Oncology 65th Annual Meeting ASTRO 2023, October 1-4, 2023, San Diego, CA

DOI

10.1016/j.ijrobp.2023.06.1600

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